The practice of offering payment to individuals in exchange for their
participation in clinical research is widespread and longstanding. Nevertheless, such payment remains the source of substantial debate, in particular about whether or the extent to which offers of payment coerce and/or unduly induce individuals to participate. Yet, the various laws, regulations, and ethical guidelines that govern the conduct of human subjects research offer
relatively little in the way of specific guidance regarding what makes a payment offer ethically acceptable-or not. Moreover, there is a lack of definitional agreement regarding what the terms coercion and undue inducement mean in the human subjects research context.